The present study investigated the effects of selective attention on the eventrelated brain potentials (ERPs) to a chord which violated the musical context. In the experiment, both musical chord sequences which contained infrequent Neapolitan six and 7th chords, and spoken old tales were presented simultaneously via speakers. In musical sequences 80% of chords were played on piano, and remaining randomly selected 20% were played on strings. In an attend-to-music condition, twelve participants selectively listened to the music stimuli, and counted chords played on strings. In an attend-to-speech condition, participants selectively listened to speech stimuli, and reported their contents after each story. Results showed that the early right-anterior negativity (ERAN), which is thought to be elicited by a harmonically unexpected chord, was observed only in the ERPs to the Neapolitan six chord in the attend-to-music condition. This indicated that selective attention was necessary for eliciting ERAN. It is suggested that how two types of expectation (schematic and veridical) would contribute to the buildup of musical context, and to the generation of ERAN should be studied further.